function validaNumeros(event){
    return validaTecla('0123456789', event)
}

function validaTecla(valores, event) { 

    var BCK=8, //backspace 
			
    ETR=13, //return 
			
    DEL=127, //delete 			    		
			
    key,tecla; 

    
    if( event.which) { 
        tecla=event.which; 
    } else if( event.keyCode) { 
        tecla=event.keyCode; 
    } else { 
        return true; 
    }
			 
    key=String.fromCharCode(tecla); 
			
    switch(tecla) { 
			
        case ETR:
            return false;  				
        case BCK: 
			
        case DEL:
			        
            //case MIN: 
			
            //case LEFT: 
			
            //case RIGHT: 
			
            //case UP: 
			
            //case DOWN: 
			
            return true; 
			
        default:
			
            if(valores.indexOf(key)!=-1) { 
                return true; 
            } 
    } 
			    
    return false; 
} 